The present invention relates to a burner apparatus and a method of operating the burner apparatus.
A burner is known to produce oxides of nitrogen (NOx) during the combustion of fuel with an oxidant. NOx, is generally produced by the combination of oxygen and nitrogen molecules supplied by the oxidant. It is sometimes desirable to reduce the level of NOx.
A recirculating dryer can have a process chamber in which hot gases from a burner are used to heat and dry parts. The process chamber can have open ends through which the parts to be heated and dried can be moved into and out of the process chamber. Because the ends of the process chamber are open, the hot gases used to heat and dry the parts can exfiltrated, that is, be lost to the atmosphere. Exfiltrated gas is replaced with make-up air. Also, air can infiltrate the recirculating dryer through the open ends of the process chamber and through access doors located along the length of the dryer.
Heating the infiltrated and/or make-up air from ambient temperature to the process temperature may require an increased amount of fuel to be combusted in comparison to a similar heating process that does not have infiltrated air or exfiltrated gas. An increased amount of fuel combustion may produce higher levels of NOx.
The present invention provides an apparatus including a housing defining a process chamber and having an opening through which gas can exfiltrated out of the process chamber. The apparatus also includes a burner operative to fire into a combustion chamber to heat gas. A collector structure is located outside the opening. The collector structure is configured to collect air and exfiltrated gas from an outside area adjacent to the opening. A duct structure communicates the collector structure with the burner so as to supply the collected air and exfiltrated gas to the burner and thereby to supply combustion oxidant to the burner.
In a preferred embodiment, the invention can further include a blower operative to drive a flow of air across the outside area and into the collector structure such that the flow of air entrains and carries gas into the collector structure. In another preferred embodiment, the apparatus can include a plenum structure defining a plenum communicating the opening with the duct structure. The plenum structure has a first open end adjacent to the opening and a second open end remote from the opening.
The present invention defines a method including firing a burner into a combustion chamber. The method also includes directing hot gas from the combustion chamber to a process chamber. The process chamber has an opening through which gas can exfiltrated. The method further includes collecting air and exfiltrated gas from an outside area adjacent to the opening into a collector structure. Directing the air and exfiltrated gas from the collector structure through the duct structure to the burner to supply the air and exfiltrated gas as combustion oxidant to the burner is further included in the method. Additionally, the method can include directing a flow of air across the outside area, and entraining exfiltrated gas in the flow of air.
The present invention also defines a method including firing a burner into a combustion chamber. The method further includes collecting air and exfiltrated gas from an outside area adjacent to an opening into a collector structure. The method also includes directing the air and exfiltrated gas from the collector structure through the duct structure to the burner to supply the air and exfiltrated gas as combustion oxidant to the burner. Additionally, the method can include directing a flow of air across the outside area, and entraining exfiltrated gas in the flow of air.